This is an application for partial funding of a meeting that is the fifth in a series of International Lymphokine Workshops. This year's theme will be "The Molecular Basis of Lymphokine Action". The Workshop will be held January 18-22, 1987 in Clearwater, Florida, which will provide a "closed" environment, free from the distractions of a big city yet easily accessible to the participants. The organizers of this event are Drs. Cohen, Pierce, and Webb, assisted by a Scientific Advisory Committee with international representation. It is anticipated that, as in the past, this meeting will help achieve new collective insights into the relationship of lymphokines to other regulatory macromolecules. This year, building on a recent explosion of information about the molecular structure of many of the lymphokines, special attention will be paid to their mechanism of action on the molecular level, including mediator-receptor interactions, intracellular activation pathways, and intercellular communication. As before, we hope to foster discussions leading to unifying concepts regarding nomenclature, standardization of assays, etc. In addition, we hope to define the background information that will make possible a rational approach for the use of lymphokines as therapeutic agents. Finally, we hope to define and clarify new problems, directions, and approaches for both basic scientific investigation and clinical applications.